Morbidity and mortality among exclusively breastfed neonates with medium-chain acyl-CoA dehydrogenase deficiency

Purpose: Despite greatly improved morbidity and mortality among infants with medium-chain acyl-CoA dehydrogenase deficiency (MCAD) since the implementation of universal newborn screening, (NBS), a population of neonates still becomes ill before their positive screen results are available. Exclusive breastfeeding is a proposed risk factor in this group. Since initial studies of MCAD NBS, breastfeeding rates have increased substantially. In this study, we quantify the current risk of early decompensation in neonates with MCAD and identify factors associated with poor outcomes. Methods: We completed a retrospective analysis of neonates with MCAD referred to our center between 2010 and 2015. Results: Of 46 infants with MCAD, 11 (23.9%) were symptomatic before the return of the NBS results. Four died or had cardiac arrest; the remaining seven had lethargy and hypoglycemia. All symptomatic patients were exclusively breastfed; only 40.6% of asymptomatic patients were exclusively breastfed. Breastfeeding rates increased from 45.5% in 2010-2011 to 64.7% in 2012-2013 and 87.5% in 2014-2015. Over these same periods, rates of early decompensation increased from 9.09% to 23.5% and 75%, respectively. Conclusions: Exclusively breastfed neonates with MCAD are at risk for early metabolic decompensation. As breastfeeding rates increase, close management of feeding difficulties is essential for all neonates awaiting NBS results.